Field of the Invention
The present invention relates to a process for improving the selectivity of a gas separation membrane wherein a monomeric material is applied to the surface of the membrane and allowed to polymerize to effectively seal defects in the membrane.
Prior Art
U.S. Pat. No. 3,325,330 discloses a multicomponent gas separation membrane comprising a porous membrane coated with the lamination of two films, thus reducing the likelihood of defects protruding through the coating.
U.S. Pat. No. 3,874,986 and U.S. Pat. No. 3,980,456 disclose a multicomponent gas separation membrane comprising a laminate on a porous membrane.
U.S. Pat. No. 4,230,463 discloses a multicomponent gas separation membrane comprising a coating on a porous membrane.
EPO No. 0 107 636 discloses a multicomponent gas separation membrane comprising a porous anisotropic substrate membrane and a coating which is the condensation product of a silanol terminated poly(dimethylsiloxane) and any of certain cross linking compounds.
U.S. Pat. No. 4,575,385 discloses a multicomponent gas separation membrane comprising a porous anisotropic substrate membrane and a coating of monomeric permeation modifiers.
U.S. Pat. No. 4,634,531 discloses a multicomponent reverse osmosis separation membrane comprising a porous anisotropic substrate membrane and a coating which is the condensation product of amines and aldehydes.
U.S. Pat. No. 4,654,055 discloses a multicomponent gas separation membrane comprising a porous anisotropic substrate membrane and a coating comprising a Lowry-Bronsted base.
U.S. Pat. No. 4,659,474 discloses multicomponent ultrafiltration and reverse osmosis separation membranes comprising a porous anisotropic substrate membrane and a coating which is the condensation product of a polyethylene imine and any of certain crosslinking compounds.
U.S. Pat. No. 4,613,625; U.S. Pat. No. 4,661,526; and U.S. Pat. No. 4,668,706 disclose a multicomponent ultrafiltration separation membrane comprising an aliphatic polyamide porous anisotropic substrate and a coating which is the condensation product of the substrate and any of certain crosslinking compounds.
U.S. Pat. No. 4,484,935 discloses a multicomponent gas separation membrane comprising a porous anisotropic substrate membrane and a coating which is the condensation product of reactive poly(dimethylsiloxane) with and any of certain crosslinking compounds with modified silane monomers.
U.S. Pat. No. 4,505,985 discloses a multicomponent separation membrane comprising a porous substrate membrane and a coating based on silicic acid heteropolycondensates produced by hydrolytic polycondensation of a silicic acid derivative in the presence of water with an optional condensation catalyst and modifiers.
Japanese Patent Application Publication Kokai: 57-94307 discloses a multicomponent reverse osmosis separation membrane comprising a dry composite semipermeable membrane treated with an aqueous surfactant solution.
Japanese Patent Application Publication Kokai: 61-107921 discloses a multicomponent gas separation membrane comprising a porous substrate and a coating which is the condensation product of a reactive acetylene monomer with a catalyst.